The strong coupling constant $\alpha_s(m_Z)$ is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of $\alpha_s(m_Z)$ at the Z-boson mass m Z are studied as a function of...
An improved determination of electroweak (EW) parameters using H1 inclusive neutral current and charged current DIS cross sections is presented. The analysis benefits from the usage of the previously published cross sections using longitudinally polarised lepton beams. The parameters are determined in a combined fit of EW parameters together with PDFs. The predictions include NNLO QCD...
In the HHT QCD fit the standard DGLAP evolution was augmented by including an additional low-x higher-twist term in the description of the longitudinal structure function, F$_\rm{L}$. This additional term significantly improves the description of the HERA reduced cross sections at low Bjorken-x and low four-momentum-transfer squared, Q$^2$. Since the HHT fit describes well data from the...
The production of multi-jet final states at hadron colliders probes pQCD at several mass scales. The processes can also be used to probe the gluon density function of the proton. The ATLAS collaboration has used multi-jets events, recorded at a center of mass energy of 8 TeV, to measure the transverse energy-energy correlations, its asymmetry and the dijet azimuthal decorrelation. These...
IceCube is a 1 cubic kilometer size neutrino detector located at the South Pole. It is capable of detecting all-sky neutrinos of all flavors from GeV to EeV energies. After detector completion, it discovered and measured the flux of extraterrestrial neutrinos in the TeV - PeV energy range, alongside with flux of neutrinos of known atmospheric origin. In this talk we will present a novel...
The production of prompt isolated photons at hadron colliders provides a stringent test of perturbative QCD and can be used to probe the gluon density function of the proton. The ATLAS collaboration has performed precise measurements of the inclusive production of isolated prompt photons at a center-of-mass energy of 13 TeV, differential in both rapidity and the photon transverse momentum. In...
Albeit initially designed for b-physics, LHCb has demonstrated to function very well as a general-purpose forward detector, covering the pseudo-rapidity range 2 < eta < 5.
Several measurements concerning the production of W, Z and top have been performed using LHCb data. A selection of relevant results will be presented, highlighting LHCb's new measurement of tt production at \sqrt{s}=13 TeV.
Measurements of the Drell-Yan production of W and Z/gamma bosons at the LHC provide a benchmark of our understanding of perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed high precision measurements at center-of-mass energies of 7 and 8 TeV. The measurements are performed for W+, W- and Z/gamma bosons integrated and as a function of the...
The production of prompt photons in association with jets in proton–proton collisions provides a testing ground for perturbative QCD (pQCD) with a hard colourless probe less affected by hadronisation effects than jet production. The measurements of the angular correlations between the photon and the jets can be used to probe the dynamics of the hard-scattering process. We present here a...
Results of the QCD analysis of a variety of the
hard-scattering data is over-viewed with a particular
focus on determination of the quark distributions in the nucleon.
A potential of the recent precise data collected at the LHC
for the problem of quark species disentangling is discussed and
compared to the impact of the low-energy fixed-target data
Finally, remaining challenges and...
We discuss the most recent updates to the PDFs obtained in the MMHT framework.
We study of the impact of the most recent LHC data and in particular focus on issues in finding good fits to these data given the very high precision now
available and the implications for PDFs and their uncertainties.
We present the recent progress on parton distribution functions (PDF) of the proton from the CTEQ-TEA collaboration.
We present a new set of parton distributions, NNPDF3.1, which updates NNPDF3.0, the first global set of PDFs determined using a methodology validated by a closure test. The update is motivated by recent progress in methodology and available data, and involves both. On the methodological side, we now parametrize and determine the charm PDF alongside the light quarks and gluon ones, thereby...
In the present paper, the ATLAS inclusive $W^{\pm}$ and $Z$ boson production data are analysed together with the CMS inclusive $W^{\pm}$ and $Z$ boson production data to investigate any possible tensions between the data sets and to determine the strange sea fraction, within the framework of a parton distribution function fit at next-to next-to leading order in perturbative QCD.
The sensitivity of CMS measurements to Parton Distribution Functions, strong coupling constant and treatment of heavy flavours in QCD analyses is presented. CMS data collected at various center-of-mass energies and their impact on the PDFs are presented. Measurements of cross sections of jet and to-quark pair production are in particular sensitive to the gluon distribution in the proton and...
We use for the first time experimental data for the inclusive heavy quark (D0, J/Psi, B->J/Psi and Y(1S) mesons) production in proton-lead collisions at the LHC in order to improve our knowledge of the gluon momentum distribution inside heavy nuclei. We observe that the nuclear effects encoded in both most recent global fits of nuclear parton densities at next-to-leading order (nCTEQ15 and...
We use nCTEQ15 nPDFs with uncertainties to identify measurements which
have a potential impact on nuclear corrections and flavor
differentiation. In particular, recent LHC W/Z vector boson production
data in proton-lead and lead-lead collisions are quite sensitive to
heavier flavors (especially the strange PDF). This complements the
information from neutrino-DIS data. As the proton flavor...
We discuss the implications of the (preliminary) CMS dijet data from 5.02 TeV pp and pPb collisions for gluon PDFs of the proton and nuclei. The preliminary pp data show a discrepancy with NLO predictions using CT14 and MMHT14 PDFs. We find that this difference cannot be accommodated with the associated scale uncertainties and debate the possible changes needed in the gluon PDFs. A similar...
SeaQuest at FNAL is a fixed-target experiment to measure the Drell-Yan process in $p+p$ and $p+A$, using the 120-GeV proton beam and targets of liquid hydrogen, liquid deuterium, carbon, iron and tungsten. During the course of operations, completed in July 2017, it recorded data from $1.4\times 10^{18}$ protons on the various targets.
SeaQuest aims at precisely measuring the flavor asymmetry...
We present the xFitter project which provides an open-source software framework for the determination of the proton's parton distribution functions and for the interpretation of the physics analyses in the context of Quantum Chromodynamics. The project has been used recently for a number of analyses performed by the LHC collaborations and theory community, which are summarised briefly. The...
The fastNLO and APPLgrid projects provide a fast and flexible way to reproduce the results of perturbative QCD cross section calculations with any input parton distribution functions. The latest developments from these projects
are presented with particular emphasis on the common APPLfast interface to the NNLOJET calculation for general cross section calculations at next-to-next-to-leading...
In this talk, we present a dedicated analysis of existing Monte Carlo methods in global QCD analysis. We critically examine the interpretability of uncertainties on extracted quantities, such as parton densities or fragmentation functions against nested sampling and more traditional approaches using Hessian methodology. We discuss how in some cases the inclusion of resampling, partition, and...
Which hadronic experiments constrain the PDF dependence of the Higgs boson cross section? What constrains the strangeness PDF better: LHC vector boson production, (SI)DIS, or jet production? We present a new technique to quantitatively answer such questions without performing a full PDF fit or PDF reweighting. The technique employs the Hessian method and takes into account the (un)correlated...
The LHC is bringing us lots of very precise measurements. The calculation of the corresponding theoretical prediction with the same precision is very time consuming in general. It is then a very challenge work to study the impact on Parton Distribution Functions(PDFs) from the precision measurements efficiently. We propose to boost the procedure by using ePump, the Error PDF Updating Method...
Precision phenomenology at the LHC requires accounting for both higher-order QCD and electroweak corrections as well as for photon-initiated subprocesses. Building upon the recent NNPDF3.1 fit, in this work the photon content of the proton is determined within a global analysis supplemented by the LUXqed constraint relating the photon PDF to lepton-proton scattering structure functions:...
We describe the inclusion of the photon as an additional component of the proton in the MMHT framework. The input for the photon is based very directly on the recent LUX determination. We describe the similarities and differences above the input scale and the contribution from both leading twist and higher twist contributions, and their uncertainties. We study the impact on the other PDFs and...
Fits to the final combined HERA deep-inelastic scattering cross-section data within the conventional DGLAP framework of QCD have shown some tension at low x and low Q2. A resolution of this tension incorporating ln(1/x)-resummation terms into the HERAPDF fits is investigated using the xFitter program. The kinematic region where this resummation is important is delineated. Such high-energy...
We report a new QCD global analysis with a simultaneous extraction of polarized and unpolarized parton densities and fragmentation functions from the available polarized and unpolarized DIS, SIDIS and SIA data sets
We present a determination of parton densities at NLO obtained with the Parton Branching method using HERA precision data. The parton densities are obtained with the standard and angular ordering evolution scales. For integrated pdfs a significant effect is observed.
The transverse momentum dependent (TMD) densities, automatically obtained with the Parton Branching method, are applied to LHC...
In this contribution I will present a determination of the Fragmentation Functions (FFs) of unidentified charged hadrons at next-to-leading order in quantum chromodynamics based on the NNPDF methodology. The analysis includes cross-section data for single-hadron production in electron-positron annihilation, from a variety of experiments, and in proton-(anti)proton collision from the Tevatron...
We study the kaon multiplicity of semi-inclusive DIS off the deutron target with the updated parton distribution functions and fragmentation functions and compare our result with the HERMES data and COMPASS data. We demonstrated the tension between the HERMES data and COMPASS data and will provide our opinion about this tension. We will make comment about the extarcted values of the strange...
The $K^−$ over $K^+$ multiplicity ratio is measured in deep-inelastic scattering, for the first time for kaons carrying a large fraction z of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160 GeV muon beam and an isoscalar $^6$LiD target. The regime of deep-inelastic scattering is ensured by requiring $Q^2>1$ (GeV/$c)^2$ for the photon virtuality and...
In this talk I will present preliminary results on π+, π- and π0 multiplicity ratios measured as a function of multiple kinematical variables in semi-inclusive DIS on three nuclei (C, Fe, Pb) normalized to deuterium . The series of measurements were performed at Jefferson Lab with 5.014 GeV electron beam incident on a double-target system in which liquid deuterium and one of the solid targets...
The bottomonium spectrum up to n = 3 is studied within Non-Relativistic Quantum Chromodynamics up to N3LO. We consider finite charm quark mass effects both in the QCD potential and the MS-pole mass relation up to third order in the Upsilon-scheme counting. The u = 1/2 renormalon of the static potential is canceled by expressing the bottom quark pole mass in terms of the MSR mass. A careful...
